The invention in general relates to ground connector assemblies for substrates and, more particularly, to a method and apparatus for securing a ground member having substrate strain relief.
Electrical circuits on thin, flexible substrates are used in a variety of applications including automotive control modules. Thin substrates are typically fabricated from a nylon material, such as a polyimide. There is an increasing interest in using less expensive materials for the substrate. Thin FR4 sheets are less expensive than polyimide sheets; however, FR4 is more rigid than polyimide. As explained in more detail below, the use of a more rigid material may cause failures from strain by the substrate due to thermal changes.
Electrical circuits need to be grounded for electrical functionality and electrical magnetic interface (EMI) reasons. Existing ground connectors on thin substrates use a solder connection between the circuit and a metallic ground plate. As explained above, FR4 is more rigid than polyimide. However, it has been found that failure of the ground connector may occur due to strain and flex of the substrate at varying operating temperatures. This is especially prevalent in automotive environments where temperatures may drastically change. In particular, during typical operating thermal cycles, the increased strain by some substrates may cause the ground connector to actually separate from a metallic ground platexe2x80x94leaving the electrical circuit at fault due to an open ground connection.
Accordingly, there is a need for reducing the strain causing by thermal changes of a thin substrate. Reducing strain allows the use of less expensive, but more rigid, substrates. This is especially important in high volume applications such as electronic control modules for vehicles. It is, therefore, desirable to provide an improved assembly and method for securing a ground connector to overcome most, if not all, of the preceding problems.